In normal engineering practice the heat exchangers of a very low temperature refrigeration system are well insulated to minimize parasitic heat losses. However, when there is a need to service the unit the insulation prevents rapid warming of the heat exchanger array. Thus, it may take more than 12, 24, 48 or even 72 hours for the heat exchanger array to achieve room temperature. This is typically done as a means to troubleshoot the unit. For example, if it is suspected that the system has a leak, the unit will be turned off and allowed to warm to check the pressure of the system at room temperature. Other service work, such as charge removal, or recovery after excess accumulation of moisture or other contaminants or of certain refrigerants at the coldest parts of the system also require such warming. This creates significant periods of time during which the equipment is not available for productive operations.